Here’s three things off the top of my head.
Famotidine, for GERD (since at least 1975).
Guaifenesin, particularly during cold season.
Ibuprofen, for an assortment of (mild) RSIs, including arthritis, carpal tunnel syndrome, and tennis elbow.
The amazing thing about these cheap OTC meds is that Croesus and Louis XIV couldn’t afford any of them.